The two-way transmission of voice, video and data over a packet-switched IP network is referred to as VoIP or IP telephony. VoIP is sensitive to delays and packet loss due to the time-sensitive nature of voice traffic. Therefore, it is important that the network carrying VoIP traffic is resilient to failures, such as network interface failures.
In a particular service provider environment, VoIP is provided over a decomposed architecture. The decomposed architecture includes a number of media gateways that provide an interface to a phone network and an IP network, such as a public switched telephone network (PSTN) and the Internet. The media gateways are connected to a number of IP routers over through asynchronous transfer mode (ATM) virtual circuits (VCs), in which the IP routers are connected to an IP network.
This VoIP architecture provides for additional protection against failure by providing multiple IP routers. However, in the event of an IP network interface failure, a media gateway has no way of receiving notice of the failure. For example, in the event of a network interface failure, the media gateway would continue to forward traffic to the router involving the network interface failure. This is undesirable because there is a disconnection in the traffic which, if it lasts for too long (typically greater than three seconds) results in one or both of the parties terminating the call.